The extinction event that wiped out all nonbird dinosaurs about 66 million years ago also shook up shark evolution.

Fossilized shark teeth show that the extinction marked a shift in the relative fates of two groups of sharks. Apex predators called lamniformes, which include modern great white sharks, dominated the oceans before the event, which took place at the end of the Cretaceous...

A newly identified dinosaur’s evolutionary origins are written all over its face.

Bony knobs studding the head and snout of Akainacephalus johnsoni, a type of armored dinosaur called an ankylosaurid, are similar to those of Asian ankylosaurids. That was a surprise, says Jelle Wiersma, a paleontologist at James Cook University in Townsville, Australia. He and Randall Irmis, a...

The first known fossil remains of a baby snake have turned up in a hunk of amber found in Myanmar. The critter, a new species named Xiaophis myanmarensis, met its untimely demise about 99 million years ago, during the Cretaceous Period, an international team of researchers reports July 18 in Science Advances.

About 540 million years ago, the oceans were an alien landscape, devoid of swimming, or nektonic, creatures. Some scientists have hypothesized, based on fossil evidence, that swimmers suddenly dominated in the oceans during the Devonian Period, between 419 million and 359 million years ago. But an in-depth study of marine fossils now suggests that this so-called Devonian Nekton Revolution...

For sauropods — the largest animals known to have walked on Earth — there may have been more than one way to get gigantic.

Most early relatives of the herbivorous dinosaurs have a suite of features once thought to be the essential blueprint for gigantism, such as sturdy pillarlike legs, elongated necks and forelimbs, and bones that grew continuously rather than in seasonal spurts. But an...

Just before humans evolved, whales and dolphins were, pound for pound, the brainiest creatures on Earth. Another cetacean superlative: Today’s biggest whales are heftier than the largest dinosaurs that ever lived. The evolutionary trends that produced big, brainy marine animals are just a few of the fascinating tales told in Spying on Whales...

Around 13,000 years ago, Earth was emerging from its last great ice age. The vast frozen sheets that had covered much of North America, Europe and Asia for thousands of years were retreating. Giant mammals — steppe bison, woolly mammoths and saber-toothed cats — grazed or hunted across tundra and grasslands. A Paleo-Indian group of hunter-gatherers who eventually gave rise to the Clovis people...

About 99 million years ago, tiny frogs hopped through a wet, tropical forest — and an unlucky few ran afoul of some tree sap. Four newly described frog fossils, preserved in amber, offer the earliest direct evidence of ancient frogs living in a humid tropical clime — just as many modern amphibians do.

None of the frog fossils is complete, making it difficult to place the frogs within...

A little animal that washed out to sea 240 million years ago off the coast of what’s now Italy turns out to be the oldest known fossil of a lizard.

The identification pushes back the fossil record of snakes and lizards by about 75 million years, says Tiago Simões of the University of Alberta in Edmonton, Canada. He and colleagues used observations of the fossil, called Megachirella...